1. Field of the Invention
The present invention relates to printed circuit boards having components secured to opposing sides.
2. Background of the Related Art
Printed circuit boards are used as the primary platform upon which a computer hardware system is constructed. Integrated circuits, power sources, input/output devices, and other component subsystems within a given compute node communicate with each other through one or more printed circuit boards. The primary printed circuit board in a compute node, along with the component secured to board, is commonly referred to as a motherboard. A secondary printed circuit board that expands the functionality of the motherboard is referred to as a daughter card.
In a multi-node chassis, a printed circuit board referred to as a midplane is also used to provide means of communication between multiple compute nodes and various chassis resources, such as a network switch, a management controller, a power supply, and a computer readable storage device. In a storage subsystem, multiple computer readable storage devices, such as disk drives, may be coupled to a printed circuit board referred to as a backplane. Ideally, the backplane will accommodate a large number of disk drives on a tight pitch. However, arranging disk drives closely together on the backplane presents a problem with component placement and signal routing due to the mechanical through-hole locating pins associated with the drive connectors.
Presently, the placement of components on the backplane is accommodated in several different ways. First, the number of disk drives may be reduced to provide additional pitch or spacing between the locating pins for component placement. However, the reduced number of disk drives also provides reduced system storage capacity and performance. In a second approach, the mechanical locating pins are no longer used such that disk drives must rely upon other means for aligning with the backplane. Unfortunately, removing the locating pins presents a manufacturing problem with holding the connector alignment relative to the mechanical enclosure that supports the drive. For example, this causes a particular problem during surface mount solder reflow process. In a further approach, a daughter board may be added to secure additional components. Still, adding daughter cards, connectors and mounting hardware to the system increases the cost of the system, while also presenting challenges to airflow and packaging issues.